Poster
in
Workshop: Mathematics of Modern Machine Learning (M3L)
Near-Interpolators: Fast Norm Growth and Tempered Near-Overfitting
Yutong Wang · Rishi Sonthalia · Wei Hu
Abstract:
We study linear regression when the input data populationcovariance matrix has eigenvalues λi∼i−α where α>1.Under a generic random matrix theory assumption, we provethat any near-interpolator, i.e., β whose training error is below the noise floor, must have its squared ℓ2-norm growing super-linearly with the number of samples n:‖β‖22=Ω(nα). This implies that existing norm-based generalization bounds increase as the number of samples increases, matching the empirical observations from prior work.On the other hand, such near-interpolators when properly tuned achieve good generalization, where the test errors approach arbitrarily close to the noise floor.Our work demonstrates that existing norm-based generalization bounds are vacuous for explainingthe generalization capability of \emph{any} near-interpolators.Moreover, we show that the trade-off between train and test accuracy is better when the norm growth exponential is smaller.
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